1. Field of the Invention
The present invention relates to the field of print finishing. It relates to a stack or a collection of essentially flat primary products. It also relates to a method for producing such a stack or such a collection.
2. Discussion of Related Art
Advertising material such as leaflets, flyers, catalogues, hand bills, direct mail but also product samples, CDs etc. in the form of primary products are currently increasingly commonly being distributed directly by special service providers. Advertising material is often combined from different providers and distributed together in order to keep distribution costs low. The advertising material or primary products that are distributed together then form a stack of (individual) single copies lying loosely one on top of the other, or a collection of single copies lying side by side, which stack must be made up by hand in each case by the distributor at the delivery location. However, this manner of making up stacks is time-consuming and error-prone, so that either multiple copies of certain pieces of advertising material are contained in the stacks or collections formed, or the material is omitted altogether.
Stacks are here essentially understood to be combinations of primary products which lie one on top of the other and are held together by gravity. If the primary products are arranged in a different spatial orientation, for example lying vertically side by side, they are then referred to as a collection. The invention relates to such different manners of combining the primary products.
It is, however, also conceivable that the stacks of primary products are formed centrally and then passed on for distribution, as is disclosed, for example, in WO2010/051651 A2 filed by the Applicant. In this case, during distribution the primary products can easily shift inside a stack or stacks can be mixed up if special precautions are not taken to hold the individual stacks together and distinguished from one another.
It is thus, for example, possible to provide the stack of advertising material or primary products with a heat-sealed foil wrapper to hold the stack together and distinguish it from other stacks. Such an additional packaging for the stacks makes distribution considerably simpler but entails relevant additional expense and may be undesirable from an ecological point of view. Moreover, the heat-sealed foil bags are awkward for the end consumer to open and the overall impression is not particularly aesthetic, depending on the material used.
The stacks can, however, also be tied up or bundled up in a different way, for example with a wrapping. For example, it would be conceivable for the stack of primary products to be collected together with a band, as is disclosed, for example, in CH 461 248. However, the same disadvantages largely result here as were mentioned above.
Moreover, a method is disclosed in EP 0 666 186 A1 in which primary products are tipped into a folded newspaper which then functions as a wrapping for the tipped-in primary products and is then closed by means of one or more adhesive strips (see also WO 2007/067325 A2). To achieve this, a newspaper needs to be provided or a separate wrapping, which in turn significantly increases the expense.
Lastly, it is disclosed in U.S. Pat. No. 5,096,176 to separate individual part stacks of sheets from other part stacks in a larger combined stack by non-adhesive paper strips (column 1, lines 58-62) being placed around one edge of the respective part stack as separating strips. The intention hereby is to prevent the separating strips, which otherwise are laid flat between two part stacks, from shifting. Non-connecting separating strips of this type are suitable only for separating inside the combined stack as the separating strips immediately fall away when a part stack is itself individually transported or otherwise handled separately.
Another problem arises when multiple primary products are to be tipped into a folded newspaper as inserts. The document DE 37 05 257 A1 filed by the Applicant describes how, in a system, first the folded newspaper is fed into corresponding compartments with the folded edge pointing downwards and opened there, before the inserts are then injected individually, one after the other, into the open newspaper by feed conveyors arranged downstream. The newspaper with the inserts is then gripped by the grippers of a removal conveyor and conveyed away. If the inserts are to be tipped in at the same rate as the high production speed of the newspaper coming directly from the web-fed printing press, the inserts must be produced in advance and temporarily stored, for example in the form of reels, separately for each type of insert, before being removed from storage again so that they can be tipped in.
The method would be significantly simplified if, for example using a system as in the abovementioned WO2010/051651 A2 filed by the Applicant, first complete stacks of all the inserts or primary products provided for a newspaper are formed, then stored temporarily, again in the form of reels or the like, and finally removed from storage so that they can be tipped into the newspaper.
However, the drawback of such temporary storage is that the inserts or primary products combined to form a stack do not in themselves have sufficient cohesion to allow them to be temporarily stored and then removed from storage without any problems.
In a completely different technical field, namely that of multipacks for liquids, a multipack has been proposed (EP 0 631 946) in which the individual soft packages are held together with minimal complexity both in terms of production technology and materials. The joining together of the individual soft packages proposed therein using adhesive spots or adhesive strips of a hot-melt adhesive should be absolutely sufficient for the stresses to which they are subjected during transport, storage, stacking on the shelves of shops and handling by the customers until the packs are broken up. In contrast to multi-page printed products such as, for example, brochures, the soft packages are self-contained inherently stable bodies which cannot be fanned out or folded or lose their shape in some other way. Problems with the place and type of application, and the existing product-specific requirements, are fundamentally different from the local technical field of print finishing.
This applies to an even greater extent to dimensionally stable packaging units such as, for example, those disclosed in U.S. Pat. No. 3,759,373 or U.S. Pat. No. 3,902,992.
On the other hand, it is known from the field of producing blocks of identical individual sheets of paper of the same size (sets of forms, notepads, pads of sticky notes, etc.) to join together the individual sheets of paper with an adhesive which is either introduced into holes punched beforehand along one edge (see, for example, DE 1 946 249 or GB 2 106 033) or applied to the edges of the sheets of paper on one or both sides, the sheets of paper then being laid one on top of the other and glued together (see, for example, US 2006/0065347). Such a type of binding is limited in the prior art to stacks of individual sheets of paper of the same format and same thickness. Moreover, there are no solutions here which can be applied to primary products with continuous/sequential processing in the context of print finishing.
In the field of print finishing, adhesive joining methods are, for example, used where (folded) partial products are collated by being laid one on top of the other (see, for example, EP 0 409 770 A2 filed by the Applicant) or where individual inserts are tipped into a newspaper or a comparable printed product and fixed there (see, for example, EP 1 780 035 A2 filed by the Applicant).